The analysis of intracranial pressure records is laborious and time-consuming when done manually because this type record is normally a continuous chart reflecting meaningful fluctuations in intracranial pressure over an extended period of time. To review such a chart in detail requires a considerable amount of the doctor's time and study. Moreover, periodic reviews or spot checks of such a chart may not accurately reflect the true state of the patient's condition since the chart may not be observed over the entire recording period even though the record is continuous.
It is obvious that intracranial pressure continuous charts must be thoroughly analyzed to detect pressure variations that may be significant for therapy and prognosis if the record is to have any value at all. Previous research has resulted in the use of a computer situated at a remote location to classify intracranial pressure readings into discrete pressure ranges and to construct a histogram of percentage time the intracranial pressure was within each pressure range.
A significant improvement in the analysis of intracranial pressure data has now been achieved by processing the data with a computer on-line at the patient's bedside. The on-line intracranial pressure data processor performs the necessary classification and calculations to display an amplitude analysis of the data in the familiar histogram form.
Intracranial pressure data from the transducer amplifier receiving intracranial pressure readings directly from the patient is appropriately amplified and introduced to an analog-to-digital convertor and then transmitted to a classifier which determines the pressure range of the current sample. A predetermined number, sixteen for example, of pressure ranges are provided. If the intracranial pressure sample value falls within a given pressure range, a count pulse is entered in the corresponding pressure range counter. A count pulse is also entered into the number of sample pulses processed counter. The instrument then sequentially calculates the number of pulses in each pressure range counter divided by the total number of samples processed. This percentage time calculation is performed to an accuracy of two decimal places. Each result is stored in the percentage memory. A histogram of the percentage time is presented on the front panel of the instrument. Pressure range is selectible by a display selector switch on that panel.
Additional data controlled by the display selector switch and displayed on the numerical display are: (1) the value of the last intracranial pressure data sample, and (2) the time in hours and minutes of the observation of the intracranial pressure data processed on-line.
From the foregoing discussion, it can be seen that it is a principal object of the present invention to provide an improved method and apparatus for processing of physiological information, such as intracranial pressure data, which automatically provides a visual display of meaningful information useful in diagnosis and other clinical purposes.
It is another object of this invention to provide improved apparatus and method for analysis of physiological information such as intracranial pressure acquired over a long period of time, which method and apparatus is operative to reduce the information into a form which permits analysis of the patient's condition that is of immediate interest at the patient's bedside.
It is still another object of the invention to provide an improved method and apparatus for immediate and instantaneous accumulation of intracranial pressure data in a manner not previously attainable.
It is yet a further object of the present invention to provide additional visual data such as the value of the last intracranial pressure data sample and the time in hours and minutes of the observation of the intracranial pressure data processed on-line.
The invention itself as well as the foregoing objectives and other objects, features, and advantages thereof, will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings wherein like characters of reference designate like parts throughout the several views.